Differential mobility analyzers are often used to measure the number, size and distribution of aerosol particles (Pui, D. Y. H., and Swift, D. L., Direct-Reading Instruments for Airborne Particles In Air Sampling Instruments for Evaluation of Atmospheric Contaminants (Edited by Hering S. V., and Cohen, B. S., pp. 337-368, ACGIH, Inc., Ohio (1995)). However, because these instruments are calibrated for spherical particles, the calibrations are not directly applicable for non-spherical particles and can not be used to obtain surface area and volume distributions of non-spherical particles and nanoparticle chain aggregates (NCA).
Aggregates appear in the emissions from diesel engines (Park, K., Kittelson, D. B., Zachariah M. R. and McMurry, P. H. “Measurement of Inherent Material Density of Nanoparticle Agglomerates”, J. Nanoparticle Res. 6, 267 (2004)); (Martins, J. V., Artaxo, P., Liousse, C., Reid, I. S., Hobbs, P. V., and Kaufmann, Y. J., “Effects of Black Carbon Content, Particle Size, and Mixing on Light Absorption by Aerosol from Biomass Burning in Brazil”, J Geophys. Res. 103, 32041, (1998)), and are generated in the commercial production of fine particles (Kodas, T. T., and Hampden-Smith, M., “Aerosol Processing of Materials,” Wiley-VCH, New York., 1999). They also appear in the manufacture of carbon black, silica and titania (Pratsinis, S. E., “Flame Aerosol Synthesis of Ceramic Powders”, Prog. Energy Combust. Sci. 24, 197, (1998)) as well as byproducts of many manufacturing procedures. Thus NCAs constitute an important class of materials which can not be properly or accurately monitored by use of the standard calibration for spheres.
There is thus a need for a more reliable, reproducible on-line method capable of measuring aggregate surface area and volume distributions as a function of a properly defined aggregate size. The embodiments of the present disclosure answer these and other needs.